I think I see where the author is coming from. While I don''t think every designer thinks that if you design a game for a certain genre that you have to accept all the "conditionals" associated with it, he does have a point that people tend to design from genre to idea, rather than idea to genre. In other words, game design is somewhat constrained because a certain amount of pigeonholing has already been created.
I also think something he doesn''t mention is common amongst game designers.....that the game world setting is not fully fleshed out before the game play is designed. It''s like, "I have this sci-fi game in mind", and other than designing the weapons very little else is thought out other than it''s a generic "sci fi" setting (yaawwwnnn). No though of the socio-political backdrop, of the technological resources, of the cultures, basically nothing other than the card board cut out of the things you play with. While this works to a degree, I think it can create a lot of imbalance problems, and makes sequels harder to do. But most importantly, I think it seperates the average game from the great game.
I personally look at the world setting first, then design around that. I also look at things that personally interest me...for selfish reasons. If I''m not interested in it, I doubt I could work up the work ethic to actually work on the game idea. I admittedly have some pretty strange game ideas...most of them are actually more akin to simulators than games. I''d like to see a scuba diving sim, I''d like to make a survival sim but set in the late 1800''s, and I have a few RTS games in mind. I also have a martial arts "training" game in mind....imagine an interactive game sorta like the Karate Kid/Jedi Master trains Padawan apprentice and you get an idea

But the game play would be very different than you expect...very little fighting. Some people say this is the wrong approach to designing games, that games are a business and like any business should cater to the needs of the customer rather than the needs of the designer. That''s all well and good, but I''d rather do what I enjoy even if it means just being a hobby. I work in the same building of the EA Tiburon division, but I just can''t stomach myself to actually talk to or meet anyone for contacts because I just hate Sports games. MAybe that''s a bad move on my part, but it''s just how I feel.
The world has achieved brilliance without wisdom, power without conscience. Ours is a world of nuclear giants and ethical infants. We know more about war than we know about peace, more about killing than we know about living. We have grasped the mystery of the atom and rejected the Sermon on the Mount." - General Omar Bradley